svn commit: r362555 - stable/12/sys/net

[Vincenzo Maffione]

Author: vmaffione
Date: Tue Jun 23 20:44:05 2020
New Revision: 362555
URL: https://svnweb.freebsd.org/changeset/base/362555

Log:
  MFC r362185
  
  iflib: netmap: enter/exit netmap mode after device stops
  
  Avoid possible race conditions by calling nm_set_native_flags()
  and nm_clear_native_flags() only after the device has been
  stopped.

Modified:
  stable/12/sys/net/iflib.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/net/iflib.c
==============================================================================
--- stable/12/sys/net/iflib.c	Tue Jun 23 20:41:10 2020	(r362554)
+++ stable/12/sys/net/iflib.c	Tue Jun 23 20:44:05 2020	(r362555)
@@ -793,13 +793,19 @@ iflib_netmap_register(struct netmap_adapter *na, int o
 	if (!CTX_IS_VF(ctx))
 		IFDI_CRCSTRIP_SET(ctx, onoff, iflib_crcstrip);
 
-	/* enable or disable flags and callbacks in na and ifp */
+	iflib_stop(ctx);
+
+	/*
+	 * Enable (or disable) netmap flags, and intercept (or restore)
+	 * ifp->if_transmit. This is done once the device has been stopped
+	 * to prevent race conditions.
+	 */
 	if (onoff) {
 		nm_set_native_flags(na);
 	} else {
 		nm_clear_native_flags(na);
 	}
-	iflib_stop(ctx);
+
 	iflib_init_locked(ctx);
 	IFDI_CRCSTRIP_SET(ctx, onoff, iflib_crcstrip); // XXX why twice ?
 	status = ifp->if_drv_flags & IFF_DRV_RUNNING ? 0 : 1;